P1777 code — how to fix error fast

If you retrieve the P1777 code in your car, it can be a worrying fact for your car’s transmission system. If you don’t act on time to repair the issue behind the code, it could even lead to serious transmission issues or even rebuilds.

If you aren’t an expert in the P1777 code meaning, this guide can help you figure it out and get to the bottom of the issue that triggered the code in your car. We’ll deal with the potential causes of code P1777, ways of diagnosing it, and recommend a few options for solving the code and removing it permanently.

Why you can trust REREV’s OBD2 code advice: Our automotive expert researchers with experienced mechanics undertakes a thorough research methodology to deliver precise insights on OBD codes. Find out more about OBD2 codes research process..

What does the P1777 code mean?

The P1777 OBD-II trouble code is a manufacturer-specific code that refers to a fault in the transmission control module (TCM). It is typically found in vehicles made by Nissan, Infiniti, and other Japanese automakers.

When the TCM detects a fault, it sends a signal to the engine control module (ECM) which illuminates the check engine light and stores the P1777 code. This fault can cause a number of symptoms, including harsh shifting, slipping, and hesitation.

Common causes of this code include faulty TCM software, a malfunctioning solenoid valve, or damaged wiring. Diagnostic procedures typically involve checking the transmission fluid level and condition, inspecting wiring and connections, and using specialized diagnostic equipment to test the TCM.

What causes the P1777 code?

There are several potential causes of the P1777 code, ranging from minor issues to more serious problems. Some of the most common causes of the P1777 code include:

Faulty TCM software

In some cases, the TCM may have faulty software that can cause it to malfunction and trigger the P1777 code. If this is the case, the TCM may need to be reprogrammed or replaced.

Problems with the solenoid valve

The solenoid valve is responsible for controlling the flow of transmission fluid within the transmission. If it malfunctions or fails, it can cause the transmission to shift improperly, resulting in the P1777 code being triggered.

Wiring issues

The wiring that connects the TCM to other components in the transmission system can become damaged over time due to exposure to heat, vibration, and other factors. This can cause signal interruptions and other problems that can trigger the P1777 code.

Low or contaminated transmission fluid

Low or dirty transmission fluid can cause a wide range of transmission problems, including slipping, hesitating, and harsh shifting. These symptoms can trigger the P1777 code.

Which car models does the P1777 code affect the most?

The P1777 code is a manufacturer-specific code that can occur in various car models. However, it is most commonly found in vehicles made by Nissan and Infiniti. Some of the car models that are most likely to be affected by the P1777 code include:

• Nissan Murano: Nissan Murano models are equipped with a Continuously Variable Transmission (CVT) that uses a TCM to control the transmission system. The TCM monitors the transmission system for any faults or malfunctions and will trigger the P1777 code if it detects a problem.
• Nissan Altima: The Altima is yet another car from Nissan that is affected by common transmission issues regarding the TCM which is known to cause the P1777 code to trigger.
• Infiniti G35: Just like the mentioned Nissan models, the Infiniti G35 is another car model that is affected by faulty TCM issues which are known to cause the code P1777 to activate.

How to diagnose the P1777 code

Diagnosing the P1777 code requires a thorough understanding of the transmission control module and the various components that make up the system. To diagnose the code, you will need to use specialized diagnostic tools and equipment, such as a scan tool and a multimeter. Still, it all depends on the exact issue behind the code, so here’s a list of possible options:

Checking the transmission fluid level and condition

A low or dirty transmission fluid level can cause a variety of transmission problems, including the P1777 code. Checking the transmission fluid level and condition is a crucial step in diagnosing this issue.

Inspecting the wiring and connections

Damaged or corroded wiring can cause signal interruptions and trigger the P1777 code. Inspecting the wiring and connections between the TCM and other components in the transmission system can help identify any issues.

Testing the solenoid valve

The solenoid valve controls the flow of transmission fluid within the transmission. A malfunctioning solenoid valve can cause shifting problems and trigger the P1777 code. Testing the solenoid valve can help determine if it is functioning properly.

Perform TCM software updates

In some cases, faulty TCM software can cause the P1777 code to be triggered. Updating the TCM software may resolve this issue.

How to fix the P1777 code

Fixing the P1777 code will depend on the specific cause of the issue. In some cases, a simple fix such as replacing a faulty solenoid or repairing a damaged wire may be all that is needed. In other cases, more extensive repairs may be required, such as replacing the torque converter clutch or repairing a damaged transmission valve body, so let’s take a look at all the possible solutions:

Replace the TCM

If the TCM is malfunctioning and cannot be repaired, it may need to be replaced. This often involves programming the new TCM with the appropriate software.

Repair and replace the solenoid valve

If the solenoid valve is found to be malfunctioning, it may need to be repaired or replaced. This will ensure that the flow of transmission fluid is properly controlled.

Repair the damaged wiring

If the wiring between the TCM and other components in the transmission system is damaged, it may need to be repaired or replaced. This will help ensure that signals are properly transmitted and received.

Update TCM software

If the P1777 code is caused by faulty TCM software, updating the software can resolve the issue. This often involves reprogramming the TCM with updated software.

Replace pressure control solenoid

If the pressure control solenoid is found to be faulty, it may need to be replaced. This will help ensure that fluid pressure within the transmission is properly regulated.

How to prevent the P1777 code

Preventing this from occurring in the first place is always the best course of action. Regular maintenance of your car’s transmission system can help prevent issues from developing and keep your car running smoothly.

Some of the most effective preventative measures include:

• Regularly checking and changing the transmission fluid
• Performing routine maintenance on the transmission, such as replacing the filter and cleaning the pan
• Driving your car gently and avoiding harsh acceleration or braking
• Avoiding overloading your car or towing heavy loads
• Seeking professional help as soon as you notice any issues with your car’s transmission system

By following these preventative measures, you can help ensure that your car’s transmission system stays healthy and free from issues such as the P1777 code. In the event that you do encounter this issue, however, it is important to act quickly and seek professional help to diagnose and fix the issue as soon as possible.

Our take

In the end, if you don’t fix it on time it could lead to serious transmission system faults and problems. To avoid having to pay between $2000 to $5000 for a complete transmission rebuild, we suggest you deal with this issue promptly with the help of advice from our experts laid out in this guide.